The biggest source of income is migratory fishes, such as salmon, trout, codfish, Alaskan Pollack, pacific saury, squid, and shark. When it is squid season in winter, squid gathering lights brightly light up the seas of Dokdo every night.
The underwater reefs grow much kelp, brown seaweed, spiny turban shells, and abalone and serve as an important source of income. According to the 1981 Study of Professor In Kyu Lee of Seoul National University Department of Botany:
Dokdo’s underwater vegetation is similar to those of the South Sea, Jejudo Island, other tropical regions of the Northern Hemisphere, and even the Mediterranean, but is very unique that it can be divided into a separate ecosystem.
The offshores and Daehwa Bank of Ulleungdo Island and Dokdo are where cool and warm currents interchange and form great fishing grounds.
This place is the fishery base of the East Sea that is full of various species of seafood, including squid. The size of catch from this region determines the prices of seafood in Korean market.